-11-
Mount the capacitors with 1/4” of
space between the body and the
PC board.
Bend cap over as
shown.
Figure D
Figure A
Align the notch on the socket (if any) with the notch
marked on the PC board. Solder the socket to the PC
board. Insert the IC into the socket with the notch as
shown below.
Note: If the IC is already inserted into
the socket, do not attempt to pull it out, as this will
damage the IC and socket. Instead, solder the socket
to the PC board with the IC in it.
Figure C
Mount the diodes with the
band in the correct direction
as shown on the top legend.
ASSEMBLE THE FOLLOWING COMPONENTS TO THE PC BOARD
In all of the following steps
the components must be installed on the top legend side of the PC board. The
board is turned to solder the component leads on the selector switch side
.
Band
Figure B
Lay resistor flat against the
PC board.
U1 - IC Socket 40-pin
U1 - 7106R IC
(see Figure A)
R20 - 110k
Ω
5% 1/4W Res.
(brown-brown-yellow-gold)
(see Figure B)
C2 - 100pF (101) Ceramic Cap.
(see Figure D)
R21 - 1M
Ω
5% 1/4W Res.
R22 - 1M
Ω
5% 1/4W Res.
(brown-black-green-gold)
(see Figure B)
C3 - .047
µ
F (473) Mylar Cap.
(see Figure D)
R23 - 1M
Ω
5% 1/4W Res.
(brown-black-green-gold)
(see Figure B)
C4 - .1
µ
F (104) Mylar Cap.
(may be marked 104)
(see Figure D)
R24 - 56k
Ω
5% 1/4W Res.
(green-blue-orange-gold)
(see Figure B)
U2 - 4030 IC or 4070
No IC socket used
Solder the IC to the PC board
with the notch in the direction
shown on the top legend.
C5 - .22
µ
F (224) Mylar Cap
C6 - .22
µ
F (224) Mylar Cap.
(see Figure D)
R16 - 1M
Ω
5% 1/4W Res.
R18 - 1M
Ω
5% 1/4W Res.
R17 - 1M
Ω
5% 1/4W Res.
(brown-black-green-gold)
(see Figure B)
R19 - 100k
Ω
5% 1/4W Res.
(brown-black-yellow-gold)
(see Figure B)
ZD - 1N5232 Diode
(see Figure C)
BAT - Battery Snap
Insert both wires through the
hole and mount the red wire to
the (+) hole and the black wire
to the (–) hole.
Solder the
wires from the top legend
side.
Notch
Notch
-24-
U1 (7106R) Voltage Test
1. Measure the voltage across pin 40 and pin 15 on
U1 (7106R) for 9V.
A. Check the battery connection.
B. Check for a 9V and GND short.
1. One of the ICs may be bad. Remove
one IC at a time and check voltage
again between pins 40 - 15.
2. Measure the voltage across pin 40 and pin 9 on
U1 for 3V.
A. U1 is defective.
3. Check the Main Oscillator on U1 (7106R) pins 1,
2, 3.
Pin 1
Pin 2
Pin3
4. Measure the voltage across pin 5 and pin 6 on
U1 (7106R) for 70mV - 105mV (reference
voltage).
A. Adjust VR1 so the the junction of R46,
R27 and R28 equal to 100mV.
1. Can’t set to 100mV.
a. VR1 wrong value or defective.
b. R25, R27 and R28 wrong value.
B. Can’t obtain 100mV between pin 5 and
pin 6.
1. Check R21 and R46.
Voltage/OHM Section
1. Measure across V OHM terminal and COM
terminal for 10M
Ω
(set meter in 200mV) battery
installed.
A. Lower or higher than 10M
Ω
.
1. Check resistors R1 - R6.
2. LCD readings floating.
A. Measure across the COM terminal to pin
6 on U1 (7106R) for 1M
Ω
.
1. R22 open or defective.
AC Voltage Section
1. Apply 15VAC to meter and measure pin 1 and pin
7 of U3 (358) to COM terminal with a scope
(meter on 20VAC scale).
Pin 1 to COM 0.44Vpp
A. Check DC/AC switch
B. Check C7, R29 - R32, D7, D8 and U3.
Pin 7 to COM 1.4Vpp
A. Check R33 - R36, D9, D10, C9 and U3.
2. Check pin 10 and pin 11 of U1 (7106R) with a
scope.
Waveform on pin 10 and pin 11.
A. Check C4 and R23.
0.2Vpp
If the meter is not working, perform the U1 (7106R)
Voltage Test first. This test is to verify that the IC
and Reference Voltage are operational.
Then
perform the tests that pertain to the Function that is
not working on your meter.
TROUBLESHOOTING GUIDE
